What does this research mean for the field?

Platelet catecholamine measurement is a valid method that identifies elevated platelet noradrenaline as a specific marker for nocturnal sympathetic activation in normotensive patients with obstructive sleep apnea, distinguishing them from hypertensive patients who show elevated urinary catecholamines. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

June 9, 2014Open Access

Evaluation and Validation of a Method for Determining Platelet Catecholamine in Patients with Obstructive Sleep Apnea and Arterial Hypertension

Structured PICO

Do platelet catecholamine levels accurately reflect sympathetic nervous system activation in patients with obstructive sleep apnea and arterial hypertension?

Population

154 adults (aged 30-65 years, mean age 50.8, 65 men/91 women) evaluated for obstructive sleep apnea (OSA) and arterial hypertension (HYP). Key exclusions: BMI >40 kg/m2, metabolic syndrome, pulmonary disease, NYHA class III-IV heart failure, unstable angina, atrial fibrillation, and uncontrolled hypertension. The cohort was divided into OSA+HYP (n=64), OSA (n=50), HYP (n=16), and Control (n=24).

Intervention

Measurement of platelet, plasma, and urinary catecholamines (adrenaline and noradrenaline). A subgroup of 9 patients received continuous positive airway pressure (CPAP) treatment for 1 year.

Comparator

Healthy control group (n=24) without OSA or HYP.

Outcome

Catecholamine levels (adrenaline and noradrenaline) in urine, plasma, and platelets, and their association with OSA and HYP.surrogate

Platelet noradrenaline levels may serve as a useful biomarker for nocturnal sympathetic activation in patients with obstructive sleep apnea without hypertension.

Abstract

BACKGROUND: Measurements of plasma and urinary catecholamine are susceptible to confounding factors that influence the results, complicating the interpretation of sympathetic nervous system (SNS) activity in the Obstructive sleep apnea (OSA) and arterial hypertension (HYP) conditions. OBJECTIVE: In this study, we validated a test for platelet catecholamine and compared the catecholamine levels (adrenaline and noradrenaline) in urine, plasma and platelets in patients with OSA and HYP compared with controls. METHODS: In the validation, 30 healthy, nonsmoking volunteers who were not currently undergoing treatment or medication were selected as the control group. One hundred fifty-four individuals (114 OSA, 40 non-OSA) were consecutively selected from the outpatient clinic of the Sleep Institute and underwent clinical, polysomnographic and laboratory evaluation, including the urinary, plasma and platelet levels of adrenaline (AD) and noradrenaline (NA). Patients were then allocated to groups according to the presence of OSA and/or hypertension. RESULTS: A logistic regression model, controlled for age and BMI, showed that urinary AD and urinary NA were risk factors in the OSA+HYP group and the HYP group; however, the model showed higher levels of platelet NA for OSA without HYP. After 1 year of CPAP (continuous upper airway pressure) treatment, patients (n = 9) presented lower levels of urinary NA (p = 0.04) and platelet NA (p = 0.05). CONCLUSION: Urinary NA and AD levels were significantly associated with the condition of hypertension with and without OSA, whereas platelet NA with OSA without comorbidity. These findings suggest that platelet catecholamine levels might reflect nocturnal sympathetic activation in OSA patients without hypertension.

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